<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        .a1 {
            text-decoration:line-through;
        }
        .a2 {
            text-decoration:none;
        }
        a {
            color: ;
            text-decoration: ;
        }
    </style>
</head>
<body>
<div class="a1">aaaa</div>
<div class="a2">bbb</div>
<div class="a3">cccc</div>
<div class="a4">ddd</div>
<a href="#">aaa</a>
</body>
</html>